1. Field of the Invention
The present invention relates generally to a fixation instrument for treating bone fractures. More specifically, a nail and bone screw combination used to treat a fracture of the femur including trochanteric, intertrochanteric and femoral neck fractures.
2. Background of the Invention
Orthopedic fixation systems used for stabilizing a fracture often include an internal fixation device, typically an elongated implant such as a nail, screw or pin, inserted into the intramedullary canal of the bone to stabilize the fracture and promote healing. Such fixation systems are often used with a fracture of the femur. The femur generally includes an elongated shaft, a ball shaped head that fits into the hip socket and a neck connecting the ball to the shaft. The shaft also includes a greater trochanter and a lesser trochanter.
Typically, the nail is inserted in the marrow canal of the bone and is positioned to span the fracture. Nails are also used to treat fractures of the neck, head, intertrochanter, subtrochanteric, pathologic and certain ipsilateral shaft and neck fractures of the femur. For example, if the neck of the femur sustains a fracture a bone screw inserted through an aperture in the nail spans the fracture and threadably engages the femoral head.
Typically, the aperture in the end of the nail is a smooth bore in which the bone screw rotates as it threadably engages the femoral head. Once the bone screw is suitably tightened, it is left in place during the healing process. Bone screw migration is one problem that may occur during the healing process. Specifically, during loading or movement of the femur, the bone screw may migrate or loosen, thus creating a risk of failure at the fracture. Accordingly, there is in need for a fixation instrument that resists bone screw migration and rotation.